The ability to provide cooling within a region of a combustor remains an area of interest. Gas turbine engines with high compressor discharge temperature, either through high compression ratio or high Mach flight speed, have reduced capacity for turbine cooling. That is, as the compressor discharge temperature rises, there is less ability to remove heat from the turbine. Thus, additional airflow may be desired, or the cooling capacity of the air can be increased by cooling the cooling air. Cooled cooling air is generally facilitated by bleeding a portion of the high temperature compressed air outside of the core gas path into a heat exchanger that is situated in an airstream with a lower air temperature. Heat is removed from the cooled cooling air via the heat exchanger and the air is then routed back into the core of the engine to cool the turbine hot section, and/or the compressor. In such systems, the heat exchanger may remove heat from the cooled cooling air using either a low temperature air source, or fuel as a heat sink.
Thus, heat exchangers may be employed to reduce the temperature of the compressor discharge air to provide adequate cooling capacity, but they can be bulky, intrusive, and they add complexity to the overall engine design and operation.
Accordingly, there remains a need for further contributions in this area of technology.